Herbicidal composition and method of weed control

ABSTRACT

The invention relates to a herbicidal composition, comprising a compound of formula I ##STR1## and a compound of formula II ##STR2## and/or of formula III ##STR3## or an agriculturally acceptable salt of the compound of formula II and/or III in admixture.

This is a 371 of PCT/EP/96/05489, Dec. 7, 1996.

The present invention relates to a novel herbicidal composition thatcontains a combination of herbicides suitable for selectivelycontrolling weeds in crops of cultivated plants, typically in crops ofcereals, rape, sugar beet, sugar cane, plantations, rice, cotton and,preferably, in crops of maize and soybean.

The invention further relates to a method of controlling weeds in cropsof cultivated plants and to the use of said novel composition therefor.The compound of formula I ##STR4## has herbicidal action. This isdisclosed, inter alia, in EP-A-0 273 417.

The following compounds of formulae II and III ##STR5## as well as theiragriculturally acceptable salts, in particular the alkali metal salts,ammonium salts and amine salts, are also known as herbicides(glufosinate and glyphosate) and are described, inter alia, in "ThePesticide Manual", Tenth Edition 1994, Crop Protection Publications, andthey are also commercially available.

Surprisingly, it has now been found that a combination of an activecompound of formula I with one of the above herbicides of formula IIand/or III, in a varying ratio, exerts a herbicidal effect that is ableto control the majority of weeds occurring in particular in crops ofcultivated plants preemergence as well as, preferably, postemergencewithout substantial injury to the cultivated plant.

Accordingly, the present invention provides a novel composition forselectively controlling weeds, which comprises, as active ingredient, acompound of formula I ##STR6## and a compound of formula II ##STR7##and/or of formula III ##STR8## or an agriculturally acceptable salt ofthe compound of formula II and/or III in admixture.

Suitable salt formers for the compounds of formulae II and III areamines, ammonium hydroxide as well as alkali metal hydroxides andalkaline earth metal hydroxides.

Illustrative examples of amines suitable for salt formation are primary,secondary and tertiary aliphatic and aromatic amines, typicallymethylamine, ethylamine, propylamine, isopropylamine, the four isomericbutylamines, dimethylamine, diethylamine, diethanol-amine,dipropylamine, diisopropylamine, di-n-butylamine, pyrrolidine,piperidine, morpholine, trimethylamine, triethylamine, tripropylamine,quinuclidine, pyridine, quinoline and isoquinoline, in particularethylamine, propylamine, diethylamine or triethylamine, preferablyisopropylamine and diethanolamine.

Typical examples of quaternary ammonium bases are generally the cationsof halo-ammonium salts, typically the tetramethylammonium cation,trimethylbenzyl-ammonium cation, triethylbenzylammonium cation,tetraethylammonium cation, trimethylethyl-ammonium cation, and also theammonium cation.

The novel herbicidal combination can be used against a great number ofagriculturally important weeds in crops of cultivated plants, inparticular in crops of maize and soybean, including Veronica, Galium,Papaver, Solanum, Chenopodium, Amaranthus, Xanthium, Abutilon, Ambrosia,Sagitaria, Ipomoea, Cassiastora, Datura stramonium, Sesbania exaltataand Sida spinosa.

The novel compositions are suitable for all standard methods ofapplication used in agriculture, typically preemergence application,postemergence application, which is preferred, and seed dressing.

The novel herbicidal combination is preferably suitable for weed controlin crops of cultivated plants, typically cereals, rape, sugar beet,sugar cane, plantations, rice, cotton and, preferably, maize andsoybean.

Crops will be understood as meaning also those crops that have been madetolerant to herbicides or classes of herbicides by conventional breedingor genetic engineering methods, e.g. to glyphosate or glufosinate, inparticular crops of soybean and maize tolerant to glyphosate andglufosinate.

Crops of cultivated plants which are tolerant to the components offormula II and/or III are preferably prepared by biotechnologicalmethods. The methods for the preparation of such plants which aretolerant to the compounds of formula II and/or III are described indetail in the international applications WO 86/02097 and WO 87/05627, inthe European applications EP-A 242 236, EP-A 242 246, EP-A 257 542 andEP-A 275 957 and in U.S. Pat. No. 5,188,642, U.S. Pat. No. 4,971,908 andU.S. Pat. No. 5,145,783 (EPSP synthase) and form part of the presentapplication by reference.

The novel herbicidal combination comprises the compound of formula I andthe compound of formula II and/or III in any mixing ratio, one componentusually exceeding the other. Preferred mixing ratios between thecompound of formula I and the components of formula II and/or III arenormally from 1:20 to 1:5.

The novel compositions preferably comprise the compound of formula I andthe compound of formula II or III.

The rate of application can vary over a wide range and will depend onthe nature of the soil, the type of application (pre- or postemergence),seed dressing, application to the seed furrow; no tillage applicationetc.), the cultivated plant, the weed to be controlled, the respectiveprevailing climatic conditions; and on other factors governed by thetype of application, time of application and the target crop. The novelherbicidal combination can be usually be applied in a rate ofapplication of 250 to 2500 g/ha, preferably of 500 to 1000 g/ha.

The weight ratio of the compound of formula I to the compound of formulaII and/or III in the novel formulation is from 1:100 to 1:0.001.

The herbicidal combinations of the compound of formula I with theherbicides of formula II and/or III may be used in unmodified form, i.e.as obtained in the synthesis, but preferably they are processed inconventional manner with the assistants customarily employed informulation technology to directly sprayable or dilutable solutions,dilute emulsions, wettable powders, soluble powders, dusts, granulatesor microcapsules. As with the type of compositions, the methods ofapplication such as spraying, atomising, dusting, wetting, scattering,or pouring, are chosen in accordance with the intended objectives andthe prevailing circumstances.

The formulations, i.e. the compositions containing the compounds offormulae I and II and/or III and usually one or more than one solid orliquid formulation assistant, are prepared in known manner, e.g. byhomogeneously mixing and/or grinding the herbicide with said formulationassistants, typically solvents or solid carriers. Surface-activecompounds (surfactants) may additionally be used for preparing theformulations.

Suitable solvents may typically be: aromatic hydrocarbons, preferablythe fractions containing 8 to 12 carbon atoms such as mixtures ofalkylbenzenes, typically xylene mixtures or alkylated naphthalenes;aliphatic and cycloaliphatic hydrocarbons such as paraffins, cyclohexaneor tetrahydronaphthalene; alcohols such as ethanol, propanol or butanol;glycols and their ethers and esters such as propylene glycol ordipropylene glycol ether; ketones such as cyclohexanone, isophorone ordiacetone alcohol; strongly polar solvents such asN-methyl-2-pyrrolidone, dimethyl sulfoxide or water; vegetable oils andtheir esters such as rapeseed oil, castor oil or soybean oil; and insome cases also silicone oils.

The solid carriers typically used for dusts and dispersible powders areusually natural mineral fillers such as calcite, talcum, kaolin,montmorillonite or attapulgite. To improve the physical properties it isalso possible to add highly dispersed silicic acid or highly dispersedabsorbent polymers. Suitable granulated adsorptive carriers are poroustypes, including pumice, broken brick, sepiolite or bentonite; andsuitable nonsorbent carriers are materials such as calcite or sand. Inaddition, innumerable pregranulated materials of inorganic or organicorigin may be used, especially dolomite or pulverised plant residues.

Depending on the type of compound of formula I to be formulated,suitable surface-active compounds are nonionic, cationic and/or anionicsurfactants having good emulsifying, dispersing and wetting properties.Surfactants will also be understood as comprising mixtures ofsurfactants.

Suitable anionic surfactants may be water-soluble soaps as well aswater-soluble synthetic surface-active compounds.

Suitable soaps are the alkali metal salts, alkaline earth metal salts,ammonium salts or substituted ammonium salts of higher fatty acids (C₁₀-C₂₂), e.g. the sodium or potassium salts of oleic or stearic acid, orof natural fatty acid mixtures which can be obtained, inter alia fromcoconut oil or tallow oil. Further suitable soaps are also the fattyacid methyl taurin salts.

More often, however, so-called synthetic surfactants are used,especially fatty sulfonates, fatty sulfates, sulfonated benzimidazolederivatives or alkylarylsulfonates.

The fatty alcohol sulfonates or sulfates are usually in the form ofalkali metal salts, alkaline earth metal salts, ammonium salts orsubstituted ammonium salts, and they contain a C₈ -C₂₂ alkyl radicalwhich also includes the alkyl moiety of acyl radicals, e.g. the sodiumor calcium salt of ligninsulfonic acid, of dodecylsulfate, or of amixture of fatty alcohol sulfates obtained from natural fatty acids.These compounds also comprise the salts of sulfated or sulfonated fattyalcohol/ethylene oxide adducts. The sulfonated benz-imidazolederivatives preferably contain 2 sulfonic acid groups and one fatty acidradical containing 8 to 22 carbon atoms. Illustrative examples ofalkylarylsulfonates are the sodium, calcium or triethanolamine salts ofdodecylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid, or of acondensate of naphthalenesulfonic acid and formaldehyde.

Corresponding phosphates, typically salts of the phosphoric acid esterof an adduct of p-nonylphenol with 4 to 14 mol of ethylene oxide, orphospholipids, are also suitable.

Nonionic surfactants are preferably polyglycol ether derivatives ofaliphatic or cycloaliphatic alcohols, or saturated or unsaturated fattyacids and alkylphenols, said derivatives containing 3 to 30 glycol ethergroups and 8 to 20 carbon atoms in the (aliphatic) hydrocarbon moietyand 6 to 18 carbon atoms in the alkyl moiety of the alkylphenols.

Further suitable nonionic surfactants are the water-soluble polyadductsof polyethylene oxide with polypropylene glycol,ethylenediaminopolypropylene glycol and alkylpolypropylene glycolcontaining 1 to 10 carbon atoms in the alkyl chain, which polyadductscontain 20 to 250 ethylene glycol ether groups and 10 to 100 propyleneglycol ether groups. These compounds usually contain 1 to 5 ethyleneglycol units per propylene glycol unit.

Illustrative examples of nonionic surfactants are nonylphenolpolyethoxylates, polyethoxylated castor oil, polyadducts ofpolypropylene and polyethylene oxide, tributylphenol polyethoxylate,polyethylene glycol and octylphenol polyethoxylate.

Fatty acid esters of polyoxyethylene sorbitan are also suitable nonionicsurfactants, typically polyoxyethylene sorbitan trioleate.

Cationic surfactants are preferably quaternary ammonium salts carrying,as N-substituent, at least one C₈ -C₂₂ alkyl radical and, as furthersubstituents, optionally halogenated lower alkyl, benzyl orhydroxy-lower alkyl radicals. The salts are preferably in the form ofhalides, methyl sulfates or ethyl sulfates, for example stearyltrimethylammonium chloride or benzyl bis(2-chloroethyl)ethylammoniumbromide.

The surfactants customarily employed in the art of formulation aredescribed, inter alia, in "Mc Cutcheon's Detergents and EmulsifiersAnnual", Mc Publishing Corp., Ridgewood, N.J., 1981, H. Stache,"Tensid-Taschenbuch" (Handbook of Surfactants), Carl Hanser Verlag,Munich/Vienna 1981, and M. and J. Ash, "Encyclopedia of Surfactants",Vol I-III, Chemical Publishing Co., New York, 1980-81.

The herbicidal compositions will usually contain from 0.1 to 99% byweight, preferably from 0.1 to 95% by weight, of a combination of thecompound of formula I with the compounds of formula II and/or III, from1 to 99.9% by weight of a solid or liquid adjuvant, and from 0 to 25% byweight, preferably from 0.1 to 25% by weight, of a surfactant.

Whereas it is preferred to formulate commercial products asconcentrates, the end user will normally use dilute formulations.

The formulations may also contain further ingredients such asstabilisers, vegetable oils or epoxidised vegetable oils, (epoxidisedcoconut oil, rapeseed oil or soybean oil), antifoams, typically siliconeoil, preservatives, viscosity regulators, binders, tackifiers, as wellas fertilisers or other chemical agents.

In particular, preferred formulations are made up as follows(throughout, percentages are by weight):

    ______________________________________                                        Emulsifiable concentrates                                                     herbicidal combination:                                                                       1 to 90%, preferably 5 to 20%                                 surfactant:     1 to 30%, preferably 10 to 20%                                liquid carrier: 5 to 94%, preferably 70 to 85%                                Dusts:                                                                        herbicidal combination:                                                                       0.1 to 10%, preferably 0.1 to 5%                              solid carrier:  99.9 to 90%, preferably 99.9 to 99%                           Suspension concentrates:                                                      herbicidal combination:                                                                       5 to 75%, preferably 10 to 50%                                water:          94 to 24%, preferably 88 to 30%                               surfactant:     1 to 40%, preferably 2 to 30%                                 Wettable powders:                                                             herbicidal combination:                                                                       0.5 to 90%, preferably 1 to 80%                               surfactant:     0.5 to 20%, preferably 1 to 15%                               solid carrier:  5 to 95%, preferably 15 to 90%                                Granulates:                                                                   herbicidal combination:                                                                       0.1 to 30%, preferably 0.1 to 15%                             solid carrier:  99.5 to 70%, preferably 97 to 85%                             ______________________________________                                    

The following Examples illustrate the invention without, however,limiting it in any way.

FORMULATION EXAMPLES

Combinations of the Compounds of Formulae I and II and/or III

(throughout, percentages are by weight)

    ______________________________________                                        F1. Emulsifiable concentrates                                                                  a)      b)      c)    d)                                     ______________________________________                                        combination of a compound of                                                                   5%      10%     25%   50%                                    formula I and herbicides of                                                   formula II and/or III                                                         calcium dodecylbenzenesulfonate                                                                6%       8%      6%    8%                                    polyethoxylated castor oil                                                                     4%      --       4%    4%                                    (36 mol EO)                                                                   octylphenol polyethoxylate                                                                     --       4%     --     2%                                    (7-8 mol EO)                                                                  cyclohexanone    --      --      10%   20%                                    mixture of aromatic hydrocarbons                                                               85%     78%     55%   16%                                    C.sub.9 --C.sub.12                                                            ______________________________________                                    

Emulsions of any desired concentration can be prepared by diluting suchconcentrates with water.

    ______________________________________                                        F2. Solutions    a)      b)      c)    d)                                     ______________________________________                                        combination of a compound of                                                                    5%     10%     50%   90%                                    formula I and herbicides of                                                   formula II and/or III                                                         1-methoxy-3-(3-methoxypropoxy)-                                                                --      20%     20%   --                                     propane                                                                       polyethylene glycol 400                                                                        20%     10%     --    --                                     N-methyl-2-pyrrolidone                                                                         --      --      30%   10%                                    mixture of aromatic hydrocarbons                                                               75%     60%     --    --                                     C.sub.9 --C.sub.12                                                            ______________________________________                                    

The solutions are suitable for use as microdrops.

    ______________________________________                                        F3. Wettable powders                                                                           a)      b)      c)    d)                                     ______________________________________                                        combination of a compound of                                                                   5%      25%     50%   80%                                    formula I and herbicides of                                                   formula II and/or III                                                         sodium ligninsulfonate                                                                         4%      --      3%    --                                     sodium laurylsulfate                                                                           2%      3%      --    4%                                     sodium diisobutylnaphthalene                                                  sulfonate        --      6%      5%    6%                                     octylphenol polyethoxylate                                                                     --      1%      2%    --                                     (7-8 mol EO)                                                                  highly dispersed silica                                                                        1%      3%      5%    10%                                    kaolin           88%     62%     35%   --                                     ______________________________________                                    

The compound mixture is throughly mixed with the adjuvants and thismixture is ground in a suitable mill to give wettable powders which canbe diluted with water to give suspensions of any desired concentration.

    ______________________________________                                        F4. Coated granulates                                                                           a)        b)     c)                                         ______________________________________                                        combination of a compound of                                                                    0.1%      5%     15%                                        formula I and herbicides of                                                   formula II and/or III                                                         highly dispersed silica                                                                         0.9%      2%     2%                                         inorganic carrier 99.0%     93%    83%                                        (.O slashed. 0.1-1 mm)                                                        e.g. CaCO.sub.3  or SiO.sub.2                                                 ______________________________________                                    

The compound mixture is dissolved in methylene chloride, the solution issprayed on to the carrier, and the solvent is removed under vacuum.

    ______________________________________                                        F5. Coated granulates                                                                           a)        b)     c)                                         ______________________________________                                        combination of a compound of                                                                    0.1%      5%     15%                                        formula I and herbicides of                                                   formula II and/or III                                                         polyethylene glycol 200                                                                         1.0%      2%     3%                                         highly dispersed silica                                                                         0.9%      1%     2%                                         inorganic carrier 98.0%     92%    80%                                        (.O slashed. 0.1-1 mm)                                                        e.g. CaCO.sub.3  or SiO.sub.2                                                 ______________________________________                                    

The finely ground compound mixture is uniformly applied in a mixer tothe kaolin moistened with polyethylene glycol. Non-dusty coatedgranulates are obtained in this manner.

    ______________________________________                                        F6. Extruder granulates                                                                       a)       b)      c)    d)                                     ______________________________________                                        combination of a compound of                                                                  0.1%     3%      5%    15%                                    formula I and herbicides of                                                   formula II and/or III                                                         sodium ligninsulfonate                                                                        1.5%     2%      3%     4%                                    carboxymethyl cellulose                                                                       1.4%     2%      2%     2%                                    kaolin          97.0%    93%     90%   79%                                    ______________________________________                                    

The compound mixture is mixed with the adjuvants and the mixture ismoistened with water. This mixture is extruded and then dried in astream of air.

    ______________________________________                                        F7. Dusts         a)        b)     c)                                         ______________________________________                                        combination of a compound of                                                                     0.1%      1%     5%                                        formula I and herbicides of                                                   formula II and/or III                                                         talcum            39.9%     49%    35%                                        kaolin            60.0%     50%    60%                                        ______________________________________                                    

Ready for use dusts are obtained by mixing the compound mixture with thecarriers on a suitable mill.

    ______________________________________                                        F8. Suspension concentrates                                                                   a)       b)      c)    d)                                     ______________________________________                                        combination of a compound of                                                                  3%       10%     25%   50%                                    formula I and herbicides of                                                   formula II and/or III                                                         ethylene glycol 5%       5%      5%    5%                                     nonylphenol polyethoxylate                                                                    --       1%      2%    --                                     (15 mol EO)                                                                   sodium ligninsulfonate                                                                        3%       3%      4%    5%                                     carboxymethyl cellulose                                                                       1%       1%      1%    1%                                     37% aqueous formaldehyde                                                                        0.2%     0.2%    0.2%                                                                                0.2%                                 solution                                                                      silicone oil emulsion                                                                           0.8%     0.8%    0.8%                                                                                0.8%                                 water           87%      79%     62%   38%                                    ______________________________________                                    

The finely ground compound mixture is homogeneously mixed with theadjuvants to give a suspension concentrate from which suspensions of anydesired concentration can be prepared by dilution with water.

It is often more expedient to formulate the compound of formula I andthe components of formula II and/or III individually and only to combinethem shortly before application in the applicator in the desired mixtureratio as tank mixture in water.

BIOLOGICAL EXAMPLES

Example B1: Postemergence Test

In a greenhouse, monocot and dicot test plants are raised in plasticpots with standard soil. At the 4- to 6-leaf stage they are sprayed withan aqueous suspension of the test substances prepared from a 25%wettable powder (Example F3, b)) at a dosage of 2000 g a.i./ha (500 1water/ha). The test plants are then further cultivated in the greenhouseunder optimum conditions. The test is evaluated after a test period ofabout 18 days (100%=total damage, 0%=no action). Valuations of 100 to70% (in particular of 100 to 80%) signify good to excellent herbicidalaction.

The novel compositions show a strong herbicidal action in this test. Thesame results are obtained by formulating the novel compositions inaccordance with Examples F1 to F2 and F4 to F8.

What is claimed is:
 1. A composition comprising an effective herbicidalamount of a compound of formula I ##STR9## and a compound of formula II##STR10## and/or of formula III ##STR11## or an agriculturallyacceptable salt of the compound of formula II and/or III in admixture,and an agriculturally acceptable carrier or diluent.
 2. The compositionaccording to claim 1, comprising the compound of formula I and thecompound of formula II or III.
 3. The composition according to claim 1,wherein the weight ratio of the compound of formula I to the compound offormula II and/or III is from 1:100 to 1:0.001.
 4. A method ofcontrolling undesirable plant growth in crops of cultivated plants,which comprises treating said plants or the locus thereof with thecomposition as claimed in claim
 1. 5. A method according to claim 4,wherein the cultivated plants are cereals, rape, sugar beet, sugar cane,plantations, rice, cotton, maize or soybean.
 6. A method according toclaim 5, wherein the cultivated plant is maize or soybean.
 7. The methodaccording to claim 4, which comprises treating the cultivated plants orthe locus thereof with the composition in rates of applicationcorresponding to 0.25 to 2.5 kg of total compound per hectare.
 8. Themethod according to claim 4 wherein the plants or locus thereof aretreated postemergence with the composition.
 9. A method of controllingundesirable plant growth in crops of cultivated plants which aretolerant or resistant to the compounds of formula II and/or III, whichcomprises treating said plants or the locus thereof with the compositionas claimed in claim 1.